Composite internal fixators

ABSTRACT

A multi-layer, fiber-reinforced composite orthopedic fixation device having a design selected based on a desired characteristic of the orthopedic fixation device. The design may be selected according to a model of the device, the model defining design constraints, and the design may comprise a pattern of the fiber angle for each layer. The selection of a design may be analyzed using finite element analysis to determine whether the design will comprise the desired characteristic.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/124,555, which is a national phase entry of PCT ApplicationPCT/US2009/060866 and has a § 371 date of Nov. 21, 2011, now allowed,which claims the benefit of U.S. Provisional Application No. 61/105,717,filed Oct. 15, 2008, and U.S. Provisional Application No. 61/180,403,filed May 21, 2009. The disclosure of each application is incorporatedby reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates generally to orthopedic instrumentationand more specifically to internal fixation devices.

Orthopaedic fixation devices may be used, for example, to stabilize aninjury, to support a bone fracture, to fuse a joint, or to correct adeformity. The orthopaedic fixation device may be attached permanentlyor temporarily, and may be attached to the bone at various locations,including implanted within a canal or other cavity of the bone,implanted beneath soft tissue and attached to an exterior surface of thebone, or disposed externally and attached by fasteners, such as screws,pins, and/or wires. Some orthopaedic fixation devices allow the positionand/or orientation of two or more bone pieces, or two or more bones, tobe adjusted relative to one another. Orthopaedic fixation devices aregenerally machined or molded from isotropic materials, such as metals,including titanium, titanium alloys, stainless steel, cobalt-chromiumalloys, and tantalum.

Although metal implants have been used for over a century, some problemsstill remain. For example, there is a stiffness mismatch between a metalimplant and bone. This sometimes leads to stress shielding and boneloss. Additionally, many patients are allergic to metallic implants.Finally, some metals have a significant acquisition lead time, which maydisrupt manufacturing operations.

It is often necessary to place an orthopaedic fixation device relativeto bone. Currently, there are two main techniques for obtaining correctorthopaedic fixation device depth within an intramedullary canal of abone. The first and oldest is the surgeon using radiography to visuallyalign the hole in the orthopaedic fixation device with the femoral headand neck. There is difficulty in identifying the axis of the hole in theorthopaedic fixation device with which to align with the femoral headand neck. The second and newer method is the use of alignment arms/jigsthat are attached to a drill guide. A C-arm is used to achieve aradiographic view of the implant and drill guide being placed in thebone. The alignment arm is attached to the drill guide and extends outon the anterior side of the patient. The arm contains radio-opaquemarkers that are visible on the radiograph. The marker shows theprojection of the fastener that is to go through the orthopaedicfixation device and into the femoral head, and the surgeon uses theprojection to align the implant with the femoral head.

To obtain version this is normally performed by the surgeon using aradiograph to visually determine the correct rotation of the orthopaedicfixation device relative the femoral head and neck. In a medial-lateralview, the surgeon attempts to align the screw hole or nail profile withthe femoral neck and head. Another method to attain appropriate versionis with use of a drill guide that contains a set of plates or a metalwire imbedded in it that the user aligns with the femoral head and neckusing radiography.

SUMMARY

According to one aspect of the invention, there is provided anorthopaedic fixation device, for example, an intramedullary nail or aplate, for use in supporting a bone or bone fragments, includes multiplelayers of a biocompatible plastic and a reinforcing fiber, such ascarbon fiber, to provide a laminated composite design. The design isselected to provide desired performance characteristics by selectiveorientation of the fibers within each layer. For example, thecompression stiffness, bending stiffness, including cantilever bendingstiffness, and torsion stiffness of the device can be controlled by thenumber and orientation of the plastic/fiber layers of the device. Thedevice can be designed by a system that is operable to select a designfrom among predefined designs associated with a model of the device. Thesystem analyzes the design to determine whether the design will producean orthopaedic fixation device that satisfies the desired performancecharacteristics, and outputs the design if the desired performancecharacteristics are satisfied by the design. In use, the system canreceive inputs from a user, such as desired performance values,including force, deflection, and/or stiffness values. Additionally oralternatively, the system can receive inputs including selectedcharacteristics that describe the application and/or patient, such aspediatric, geriatric, or a mineral density of the bone to be secured,and the system determines performance values for the device based on thecharacteristics and/or the other inputs.

In one embodiment, there is provided a method of designing a laminatedcomposite article comprising receiving, in a computer system,information regarding a desired characteristic of the article, selectinga model of the article based on the information, selecting amulti-layer, fiber-reinforced composite design of the article from agroup of laminated composite designs associated with the model,comparing results of a finite element analysis of the selected design tothe desired characteristic, and outputting the selected design when thecomparison indicates that the article will exhibit the desiredcharacteristic.

In another embodiment, the desired characteristic includes one of acompression stiffness, a bending stiffness, a torsion stiffness,specific patient information, generic patient information, andinformation regarding an isotropic article.

In yet another embodiment, there is provided a method of selecting amodel of the article comprises selecting a model from a library ofmodels.

In still another embodiment, the group of laminated composite designscomprises designs comprising fiber reinforced composite layers, eachlayer having a predetermined fiber angle orientation, the fiber angleorientations of the layers being symmetric about a middle of the layersof the design.

In another embodiment, the model comprises information regardingexterior and interior dimensions of the article.

In yet another embodiment, the designs are associated with a model basedon a difference between an exterior dimension and an interior dimensionof the model being less than a sum of the thicknesses of the layers ofthe design.

In still another embodiment, the selected design comprises instructionsfor manufacture of the laminated composite article.

In another embodiment, the instructions, when executed produce anorthopaedic fixation device suitable for implantation in a humanpatient.

In another aspect of the invention, there is provided an internalfixator for spanning a fracture, the internal fixator having a pluralityof layers, each layer of the plurality of layers including athermoplastic component and a fiber component and each layer of theplurality of layers having a selected fiber angle pattern, the selectedfiber angle patterns being arranged symmetrically from a first layer toa last layer, and the symmetrical arrangement of fiber angle patternsincluding at least two layers having generally opposing fiber anglepatterns.

In one embodiment of the invention, the internal fixator is one of anintramedullary nail and a bone plate.

In another embodiment, for each layer, the fibers of a layer aregenerally parallel.

In yet another embodiment, the invention also includes an apertureformed through the internal fixator for receiving a fastener.

In still another embodiment, a sleeve disposed in the aperture, thesleeve configured to receive the fastener therein.

In another embodiment, the invention includes an exterior coating of athermoplastic material with substantially no fiber component.

In yet another embodiment, the internal fixator is an intramedullarynail, the intramedullary nail comprising a head, a shaft, and atransition region between the head and the shaft.

In still another embodiment the head comprises a greater number oflayers than a number of layers of the shaft.

In another embodiment, selected fiber angle patterns of the layers areselected such that the device exhibits a selected stiffnesscharacteristic.

In yet another aspect of the invention, there is provided a method ofmaking a system for designing a laminated composite article comprisingcreating a library of models, the models defining exterior dimensions ofthe article, creating a library of laminated composite article designs,each design being associated with at least one model, and each designcomprising a multi-layer construction of the article, each layerincluding a including information regarding a fiber angle for fibers ofthe layer, coding a selection engine configured to select a design fromthe library of designs based on a selected characteristic of thelaminated composite article and for outputting a selected design, andcoding a finite element analysis engine configured to determine thatanalysis of the selected design corresponds to the selectedcharacteristic.

In one embodiment, creating a library of models comprises storingexterior dimensions of an intramedullary nail and storing a minimumdiameter of a central cavity.

In another embodiment, associating a design with a model based on adetermination that a sum of thickness of the layers of the design isless than a difference between the minimum diameter of the centralcavity and a stored outer diameter associated with the model.

In yet another embodiment, the selection engine is operable tosequentially select a design associated with the model in an orderaccording to increasing layer number.

In another embodiment, the finite element analysis engine is configuredto determine whether the selected design will provide at least one ofdesired compression stiffness, a desired bending stiffness, and adesired torsion stiffness.

In yet another embodiment, configuring the system to output the selecteddesign when the finite element analysis engine determines that theselected design corresponds to the selected characteristic.

In still another embodiment, configuring the system to select adifferent design when the finite element analysis engine determines thatthe selected design does not correspond to the selected characteristic.

In another embodiment, coding the finite element analysis enginecomprises validating that the finite element analysis engine generatestheoretical test results for designs that are similar to physical testresults of the designs.

In yet another embodiment, coding the finite element analysis enginefurther comprises adjusting a parameter of the finite element analysisengine if the finite element analysis engine does not generatetheoretical test results for designs that are similar to physical testresults for the designs.

In still another aspect of the invention, there is provided a system fordesigning a laminated composite article comprising an input deviceconfigure to receive information regarding the laminated compositearticle, at least one storage device storing a plurality of models andstoring a plurality of designs of laminated composite articles, eachdesign associated with at least one model, a selection engine forselecting a design from the plurality of designs according to the model,a finite element analysis engine for generating analysis results for theselected design, and an output device for outputting the selecteddesign.

In one embodiment, the system is configured to determine whether theanalysis results are similar to the received information.

In another embodiment, the system is configured to output the selecteddesign if the analysis results are determined to be similar to thereceived information.

In yet another embodiment, the selection engine is configured to selecta design in an order according to increasing layer number.

In still another embodiment, the information relates to at least one ofa compression stiffness, a bending stiffness, a torsion stiffness,specific patient information, generic patient information, andinformation regarding a an isotropic article.

In another embodiment, the specific patient information includes atleast one of information regarding a patient's age and informationregarding a bone mineral density of a patient's bone.

In yet another embodiment, the generic patient information includes atleast one of information regarding an age group, information regarding apatient's activity level, and information regarding a bone quality of apatient's bone.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features will beapparent from the description and drawings, and from the claims.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an orthopaedic fixation device.

FIG. 2 is a cross-sectional view of the orthopaedic fixation devicetaken along line 2-2 of FIG. 1.

FIG. 3 is perspective view of an orthopaedic fixation device inconstruction.

FIG. 4 is a perspective view of an orthopaedic fixation device.

FIG. 5 is a cross-sectional view of the orthopaedic fixation devicetaken along line 5-5 of FIG. 4.

FIG. 6 is a perspective view of an orthopaedic fixation device.

FIG. 7 is a diagram of a system for designing a laminated compositeorthopaedic fixation device.

FIG. 8 is flow chart illustrating a process for making a laminatedcomposite orthopaedic fixation device.

FIG. 9 is a flow chart illustrating a process for making the system ofFIG. 7.

FIGS. 10 and 11 illustrate an intramedullary nail in a medial-lateralview in a first embodiment.

FIGS. 12 and 13 illustrate an intramedullary nail in ananterior-posterior view in a second embodiment.

FIGS. 14-17 illustrate an intramedullary nail in a third embodiment.

FIG. 18 illustrates a sectional side view of an intramedullary nail in afourth embodiment.

FIG. 19 illustrates a sectional side view of an intramedullary nail in afifth embodiment.

FIG. 20 illustrates an intramedullary nail in an anterior-posterior viewin a sixth embodiment.

FIG. 21 illustrates the intramedullary nail shown in FIG. 20 in amedial-lateral view.

FIG. 22 illustrates an intramedullary nail in a seventh embodiment.

FIG. 23 illustrates an intramedullary nail in an eighth embodiment.

FIG. 24 illustrates a sectional side view of an intramedullary nail in aninth embodiment.

FIG. 25 illustrates the intramedullary nail in a tenth embodiment.

FIG. 26 illustrates the intramedullary nail of FIG. 25 in a sectionalview.

FIGS. 27-30 illustrate the intramedullary nail in an eleventhembodiment.

FIGS. 31 and 32 illustrate bone plates in a first embodiment.

FIG. 33 illustrates a bone plate in a second embodiment.

FIG. 34 is a bottom view of the embodiment shown in FIG. 33.

FIG. 35 illustrates a bone plate in a third embodiment.

FIG. 36 illustrates a bone plate in the fourth embodiment.

FIG. 37 illustrates a bone plate in a fifth embodiment.

FIG. 38 illustrates a bone plate in a sixth embodiment.

FIG. 39 illustrates the intramedullary nail in a twelfth embodiment.

FIG. 40 illustrates the intramedullary nail in a thirteenth embodiment.

DETAILED DESCRIPTION

Referring to FIGS. 1, 2 and 3, an intramedullary nail 100 includes ashaft 102 and a head 104. The shaft 102 defines apertures 111 forreceiving screws, or other fasteners (not shown), and the head 104defines apertures 111 for receiving pin P, screws, or other fasteners(not shown) for securing the intramedullary nail 100 within theintramedullary canal of a long bone. The fasteners may be made frommetal, polymer, or a composite material.

The nail 100 is constructed of a plurality of layers 201-213 of acomposite material, such as a polyetheretherketone (PEEK) and carbonfiber composite. The composite material can be a continuousfiber-reinforced material, such as a sheet, tape, or tow, in which thecarbon fibers are generally aligned in parallel with the lengthdimensions of the fibers oriented in the length dimension of the sheet,tape, or tow. The layers have a generally uniform thickness in the rangeof 0.01 millimeters to 4 millimeters, with some implementations having athickness of 0.14 millimeters±0.1 millimeters. The fibers of each layerare generally parallel and continuous, such that for each layer, all, orsubstantially all, of the fibers have a common angular orientationrelative to a longitudinal axis L-L of the nail 100. For example, afirst layer of the composite material can have fibers oriented generallyacross the length dimension at approximately ninety degrees to thelongitudinal axis L-L. Another layer disposed above or below the firstlayer (or inside or outside of the first layer) can have fibers orientedat a five degree angle, or another selected angle, relative to thelongitudinal axis L-L. In some embodiments, the first layer and/or thelast layer may be made from virgin PEEK (i.e., PEEK withoutreinforcement).

Because the fibers of the composite material exhibit differentmechanical characteristics in response to different forces relative totheir longitudinal axis, and because the fibers of each layer aregenerally parallel and continuous, the affect of each layer on themechanical characteristics of the nail 100 in response to differentforces is determined by the relative orientation of the fibers to thelongitudinal axis L-L of the nail 100. In many circumstances, the nail100 benefits from having at least one layer having fibers orientedacross the longitudinal axis L-L and at least one layer having fiberorientations generally along the longitudinal axis L-L. Furthermore, theorientation of the fibers of each layer of the nail 100 can be selectedsuch that the nail 100 exhibits selected characteristics in response tovarious forces. For example, the nail 100 may exhibit selected stiffnesscharacteristics in response to compression, bending, and torsion forcesby selection of the fiber orientations of each layer thereof based onspecific characteristics of the material.

The nail 100 includes a first end 100 a, a second opposing end 100 b,and a medial portion 100 c extending between the first end 100 a and thesecond end 100 b. A first section 101 includes the first end 100 a andhas a first circumference C1. A second section 103 has a secondcircumference C2 and includes the second end 100 b. Each of the firstsection 101 and the second section 103 has one or more apertures 111formed therethrough for receiving a pin P, or other fastener, such as ascrew, bolt, or rod (not shown), for connecting the nail 100 to bone.The nail 100 has a longitudinal axis L-L, and a circumference profilealong the longitudinal axis L-L adapted for implantation within a canalof a bone, such as a femoral canal, a tibial canal, a humeral canal, ora clavical canal. As illustrated, the first section 101 has a firstcircumference C1, and the second section 103 has a second, smallercircumference C2. A transition section 105 has a decreasingcircumference along the longitudinal axis L-L from the firstcircumference C1 to the second circumference C2 in the direction fromthe first end 100 a towards the second end 100 b. In someimplementations, the first circumference C1 can be approximately 13millimeters, and the second circumference C2 can be selected toapproximately match the size of the canal of the bone into which thenail 100 is inserted. The transition section 105 can have a constantslope between the first section 101 and the second section 103, or canhave a varying slope to achieve a rounded transition. It is possiblethat the second circumference C2 is approximately equal to the firstcircumference C1, and therefore, the transition section 105 can beomitted.

If a central cavity or cannulation 200 a is desired, the nail 100 isformed, for example, by wrapping a pre-impregnated PEEK carbon-fiber towaround a mandrel to form a layer. After the nail 100 is formed, themandrel is removed and the cavity 200 a remains, and extends along amajority of the longitudinal axis L-L from the first end 100 a towardthe second end 100 b. Alternatively, however, the nail can include asolid center. To form a solid nail, the mandrel remains within thelayers, or can be replaced with another material, such as abiocompatible plastic material. Furthermore, the mandrel can be formedfrom a material that is dissolved and/or absorbed by the patient. Forexample, the mandrel may be absorbed such that the nail is solid whenimplanted and a cavity develops after implantation.

The mandrel can be selected such that it has an exterior dimension thatapproximately equals a desired interior dimension of the nail.Furthermore, the shape of the mandrel may be selected to provide a nailhaving a similar shape. For example, the mandrel may be cylindrical, andmay have a circular, trapezoidal, oval, or other cross-sectional shapein order to provide a nail having such shapes. Additionally, the mandrelcan include two or more portions having different shapes, such as acircular cylinder portion associated with the shaft and a rectangularcylinder portion associated with the head. In some implementations, acircular cylinder portion of the mandrel is associated with the shaft102 of the nail 100 and a trapezoidal cylinder portion is associatedwith the head 104 of the nail 100.

During wrapping, the fibers can be routed around the apertures 111, suchas by routing the tow around guide members disposed in the locationswhere the apertures 111 will be formed. By routing the fibers around theapertures 111, the need to subsequently remove pieces of the compositematerial to form the apertures 111 in the nail 100 can be avoided.Furthermore, forming the apertures 111 using the guide members canproduce a smooth bore through the nail 100, and can avoid breaking thecarbon fibers. Optionally, the apertures can be formed using guidemembers that are larger than the desired aperture size, and a sleeve orother reinforcing or protective member can be installed within theaperture formed by the guide member to create the apertures 111 of adesired size for receiving a pin P of corresponding size. Such a sleeveor reinforcing member can reduce damage to the composite material in anarea near the apertures.

Subsequent layers can be added by wrapping the pre-impregnatedcarbon-fiber tow around the previous layer. When the layer wrapping iscomplete, the mandrel and other guides can be removed. Where a tow,tape, or ribbon is used, and as discussed above, the carbon fibers aredisposed within the layer with a length of each fiber generally parallelto the length dimension of the tow. Thus, if a layer with a ninetydegree fiber orientation is desired, the tow can be wrapped around themandrel (and previous layer, if any are present) at approximately ninetydegrees to the longitudinal axis L-L.

The nail 100 is adapted to be secured to different bones, or todifferent bone portions, via bone pins or screws (not shown) disposed inapertures 111. As such, the medial portion 100 c, which includes thetransition section 105, can be described as a working portion of thenail 100 that experiences compression, bending forces, and torsion thatare applied to the different bones or different bone portions. Forexample, in a fracture-securing application, the nail 100 can supportportions of a bone on opposite sides of a fracture, and can transfer aforce applied to one bone portion to the other bone portion whilegenerally maintaining the positions of the bone portions relative to oneanother. However, some relative movement between the bones or boneportions may be desired, or it may be desired that some portion of theforces be borne by the bone across the fracture site, during and/orafter healing. Accordingly, the physical properties of the nail 100, atleast in the medial portion 100 c, can be selected such that the nail100 exhibits acceptable bending, twisting, and compression deflection inresponse to anticipated bending, twisting, and compression forcesassociated with a selected application.

In some implementations, the first section 101 is formed without carbonfiber composite layers, at least in a proximal portion thereof, and thecircumference C1 includes a molded structure formed of the thermoplasticmaterial. In other implementations, the first section 101 includesmultiple carbon fiber reinforced composite layers including the samelayers that are included in the second section 103 having the secondcircumference, and some additional layers or thermoplastic material. Forexample, additional layers of the carbon fiber reinforced composite,such as layers having fibers oriented at 90 degrees to the longitudinalaxis L-L, can be added to create the transition section 105 and thefirst section 101 having the first circumference C1. Alternatively,thermoplastic material can be added to the outer layer of the multiplecarbon fiber reinforced composite layers to create the first sectionhaving the circumference C1 and the transition section 105.Additionally, as discussed above, the mandrel may include differentportions associated with the first section 101, the second section 103,and the transition section 105 such that application of layers over themandrel results in the desired exterior surface dimensions and shapes ofthe nail 100. A sleeve may be inserted within the central cavity 200 ato provide a cannulation of uniform dimension, or of dimensions orshapes different from the dimensions or shape of the mandrel.

Such an outer layer of thermoplastic material, or other outer coating ofmaterial can be included not only to obtain a desired outer dimension,but can also be included to provide a desired texture or other propertyover the entire exterior surface, or over portions thereof. For example,a layer of biocompatible thermoplastic material can be included toprovide a smooth exterior surface, which can aid in inhibiting growth ofbacteria colonies. Furthermore, the coating material can be selectedsuch that allergic reactions, or other undesired reactions, can bereduced or eliminated. Additionally, an outer layer and/or an innerlayer of thermoplastic material, such as PEEK, reduces carbon fiberdebris that can be created or released by interaction between aninstrument, such as a drill, with the nail 100 during implantation.Debris can also be created or released after implantation by interactionbetween a bone pin or other component during use. An outer layer and/orand inner layer of thermoplastic material can inhibit escape of detachedpieces.

The outer and/or inner layers of thermoplastic material can be formed bywrapping a tow of PEEK without fiber reinforcement. For example, aninner layer can be formed by first wrapping a tow of PEEK without fiberreinforcement around the mandrel. An outer layer can be formed bywrapping a tow of PEEK without fiber reinforcement around the outside ofa carbon fiber reinforced layer. Alternatively, a tube or sleeve ofthermoplastic material can be applied over the mandrel and/or over alast carbon fiber reinforced layer. Other techniques, such as printingor molding can also be used. Additionally, the nail 100 including suchan inner and/or outer layer of thermoplastic material can be treated,such as in an autoclave, to consolidate the layers.

In one particular embodiment, a cylindrical mandrel is provided. Themandrel may be cannulated. The mandrel may have two or more radialthrough holes spaced apart from each end. Multiple layers of braidedsleeves are placed over the mandrel. More layers may be placed on oneend of the composite than the other for thickness. The braid isseparated and pins are placed through the through holes in the mandrelfor fastener holes in the intramedullary nail. The composite isautoclaved to consolidate the layers, and the pins are removed toprovide through holes in the intramedullary nail. The mandrel thereaftermay be removed.

An additional or alternative coating layer can be added to provide otherdesired characteristics. For example, non-metallic orthopedic devicescan benefit from a coating to provide scratch resistance in order toprotect the device from mechanical abrasion experienced during thesurgical implantation procedure. The thickness of a scratch-resistantcoating is about 2±0.5 μm. A scratch-resistant coating can be applied,e.g., by plasma immersion ion processing (PIP) techniques, physicalvapor deposition (PVD), chemical vapor deposition (CVD), by dipping, orby spin coating.

The coating can be formed of diamond-like-carbon (DLC), which offersmany of the properties of diamond, producing a lubricous, wear-resistantchemical barrier suitable for long term implantation. DLC film isdeposited by starting with a carbon-containing gas such as acetylene toprovide carbon atoms to deposit onto the substrate. The mechanicalproperties of the coating can be tailored to the requirements of thedevice by simply changing the deposition conditions. Particularly, ascratch-resistant layer can be precipitated through plasmapolymerization to produce a thin, highly cross-linked layer. Examplesinclude tetraethylorthosilicate and hexamethyldisiloxane.

Adding scratch-resistant properties in the nail 100 can be achieved byadding fillers during a molding operation. The size and concentration,known as loading, of the fillers used to reinforce the composite affectthe final properties of the device. Micron-size particles are used toincrease filler content while retaining processability, and nanofillersare incorporated to increase wear resistance. Nanofillers are wellsuited for use as fillers in the composite devices described hereinbecause they will not compromise the volume fraction of the carbonfibers, and thus will not compromise flexural strength of the device.Biocompatible fillers include, but are not limited to, hydroxyapatiteand silicon carbide.

To protect the carbon fibers in a surface layer of the device frommechanical abrasion, a PEEK coating or an over-mold “skin” of PEEKmaterial can be applied. PEEK coatings have excellent substrateadhesion, and do not require a primer during the coating process.Additionally, a PEEK coating can be applied in a thin layer, whichcontributes to low manufacturing cost. Flame spraying and printing PEEKcan be used to apply such a PEEK over-mold. An amorphous PEEK coatingcan be obtained by these techniques, and can be annealed to produce amore wear resistant semi-crystalline structure, if desired. Further,overmolding may prevent fluid from contacting the carbon fibers, whichmay affect stiffness of the construct.

Mechanically-induced damage can be reduced by modifying the surfacetopography of the device or cross-sectional geometry of the apertures,such that it is difficult to skive the drill across the surface duringtargeting of the apertures. The surface could be machined by grit/sandblasting, and a chamfer or bushing located in an aperture could be usedto facilitate the location of the drill.

With reference to FIGS. 2 and 3, a cross-sectional view taken across thelongitudinal axis L-L at the medial portion 100 c illustrates a firstlayer 201 that defines the hollow central cavity 200 a. The lengthdimensions of the fibers of the first layer 201 are oriented atapproximately ninety degrees to the length dimension L. That is to say,the fibers wrap around the length dimension generally perpendicularly. Asecond layer 203 overlays the first layer 201 and can have a differentfiber orientation than the fiber orientation of the first layer 201. Forexample, a tow T having fibers oriented in length dimension of the tow Tis wrapped around the first layer 201 such that the longitudinal axis ofthe fibers of the second layer 203 are oriented at approximatelypositive forty-five degrees relative to the longitudinal axis L-L of thenail 100, where the proximal direction in the length dimension L isequal to zero degrees. A third layer 205 overlays the second layer 203and includes fibers whose length dimensions are oriented atapproximately negative forty-five degrees relative to the longitudinalaxis L-L. Thus, the orientation of the fibers of the third layer 205generally opposes, i.e., is approximately perpendicular to, theorientation of the fibers of the second layer 203.

A fourth layer 207 overlays the third layer 205 and includes fiberswhose length dimensions are oriented generally along the longitudinalaxis L-L. If the nail 100 is formed by wrapping a pre-impregnated carbonfiber reinforced tow T, the fourth layer 207 can include fibers whoselength dimensions are oriented at positive or negative five degrees fromthe longitudinal axis L-L. Thus, the orientation of the fibers of thefourth layer 207 generally opposes the orientation of the fibers of thefirst layer 201. Alternatively, including implementations where thecarbon fiber reinforced tow T is used, a layer that includes fibersoriented generally along the longitudinal axis L-L can be oriented atapproximately zero degrees, i.e., parallel to the longitudinal axis L-L.

A fifth layer 209 overlays the fourth layer 207 and includes fibersoriented at approximately negative forty-five degrees relative to thelongitudinal axis L-L, in opposition to the orientation of the fibers ofthe fifth layer 209. Additionally, the orientation of the fibers of thefifth layer generally matches the orientation of the fibers of the thirdlayer 205, and generally opposes the orientation of the fibers of thesecond layer 203. A sixth layer 211 overlays the fifth layer 209 andincludes fibers oriented generally at positive forty-five degrees fromthe longitudinal axis L-L. Thus, orientation of the fibers of the sixthlayer 211 generally opposes the orientation of the fibers of the fifthlayer 209, and generally matches the orientation of the fibers of thesecond layer 203. A seventh layer 213 overlays the sixth layer 211 andforms the outer layer of the nail 100. The seventh layer 213 includesfibers oriented generally at ninety degrees to the longitudinal axisL-L. The orientation of the fibers of the seventh layer 213 generallyopposes the orientation of the fibers of the fourth layer 207 andgenerally matches the orientation of the fibers of the first layer 201.

The pattern of the orientations of the layers 201-213 is selected toprovide medial portion 100 c with physical properties substantiallymatching the selected physical properties associated with the selectedapplication by including a number of layers with different fiberorientation. Each of the layers contributes to a stiffness in one ormore dimension, and the sum of the stiffness provided by each layerapproximately equals the selected stiffness in each dimension ofinterest. In some implementations, and as described above, the patternof the orientations of the layers 201-213 includes at least twodifferent pairs of layers having generally opposing fiber orientations.The first pair of layers having generally opposing fiber orientationsincludes the first layer 201 generally across the longitudinal axis L-L,and the fourth layer 207 generally along the longitudinal axis L-L. Thesecond pair of layers having generally opposing fiber orientationsincludes the second layer 203 at positive forty-five degrees from thelongitudinal axis L-L and the third layer 205 at negative forty-fivedegrees from the longitudinal axis L-L. It should be noted that a thirdpair of layers having generally opposing fiber orientations includes thefourth layer 207 and the seventh layer 213. However, the generallyopposing orientations of the layers of the third pair have the sameorientations of the first pair. Similarly, a fourth pair of layershaving generally opposing fiber orientations includes the fifth layer209 and the sixth layer 211, and the opposing orientations of the fourthpair are the same orientations of the second pair.

Additionally, the pattern of the orientations of the layers 201-213 ofthe nail 100 is symmetric about a middle of the pattern from the firstlayer 201 to the last layer, i.e. the seventh layer 213. As illustrated,the nail 100 includes seven layers, with the fourth layer 207 being themiddle of the layer pattern. Thus, each of the first and seventh layers201, 213 includes fibers oriented generally across the longitudinal axisL-L, disposed at approximately ninety degrees from the longitudinal axisL-L, each of the second and sixth layers 203, 211 includes fibersoriented generally at positive forty-five degrees from the longitudinalaxis L-L, and each of the third and fifth layers 205, 209 includesfibers oriented generally at negative forty-five degrees from thelongitudinal axis L-L.

Although the nail 100 has been described as having seven layers 201-213,the nail 100 can include more layers and/or different layer orientationpatterns. For example, the number of layers included in the design maybe greater or less than seven, and the orientation of the fibers of eachlayer may be different than as described above. However, the pattern oflayer orientations may still include two or more different opposingpairs of fiber orientations and/or the pattern of layer orientations maystill be symmetric from a first inner layer to a last outer layer abouta middle of the layers or a middle layer. As mentioned above, thespecific number of layers and the specific fiber orientation of eachlayer, together referred to as the design, can be selected to providethe nail 100 with desired performance characteristics during use in aselected application environment.

Referring now to FIGS. 4-6 a plate 250 includes a length dimension 251and has a curvature in a direction across the length dimension 251 toapproximately match a curvature of a bone to which the plate 250 isconfigured to be attached. Apertures 261 are included in the plate 250and are adapted to receive bone screws, or other fasteners (not shown).The plate 250 includes layers 253-259, which are analogous to layers203-213 discussed above. However, each of the layers 253-259 can beformed from a sheet of carbon fiber reinforced PEEK material thatincludes generally parallel continuous carbon fibers. The layers 253-259are arranged such that the length direction of the carbon fibers isoriented at a selected angle with respect to the length dimension 251 ofthe plate 250.

Alternatively, as illustrated in FIG. 6, the plate 250 can be formedfrom a tape, tow, or ribbon by wrapping around guide members 271 locatedin positions where the apertures 261 are desired. As illustrated, thelayer 258 is formed by substantially parallel wraps of a tow at an angleof approximately 45 degrees relative to the length dimension 251. Thelayer 258 is formed over the layer 257, which is formed by substantiallyparallel wraps of the tow T at an angle of approximately −45 degreesrelative to the length dimension 251. Other layers can include wraps ofthe tow at approximately 90 degrees to the length dimension 251, atapproximately zero degrees to the length dimension 251, or at anotherselected angle. Additionally, one or more layers of the plate 250 can beformed by weaving the tow T between the guide members 271. Also, one ormore layers of the plate 250 can be formed from a sheet, while otherlayers are formed from a tow. Accordingly, such multi-layer and/orbraided carbon fiber/PEEK implants, such as plate 250, are formed suchthat apertures 261 may be placed in the matrix without causingdiscontinuity in the fibers, which assists in maintaining implantstrength. Another advantage of such multi-layer and/or braided plates isthat they exhibit a combination of lower stiffness and relativelysmaller dimensions that allow the plates to be more easily implanted inthe limited space between bone and muscle as compared to, for example,steel plates.

FIG. 7 illustrates a system 400 that can be used to select a design forthe nail 100, or other orthopaedic fixation device. The system 400includes a selection engine 410 operable with a library of models oforthopaedic fixation devices 420, a library of patterns of layerorientations 430, a finite element analysis engine 440, and a storagedevice 450 for storing instructions for designing a laminate compositeorthopaedic fixation device, such as the nail 100. The selection engine410, the libraries 420 and 430, the finite element analysis engine 440,and the storage device 450 may be formed as components of a computersystem 490 that includes a processor, a storage device having anoperating system stored thereon, a memory module, and a system bus. Thesystem 400 can further include an input device 470 and an output device480 operable with an input/output module 460 to receive inputs from auser, such as a selection of performance characteristics, or otherdescription of a desired device for which a design is to be selected,and to provide a selected design to a user. Thus, the selection engine410 may be formed as a processor of the computer system 490 thatexecutes instructions of a computer program to select a design of alaminated composite orthopaedic fixation device. The library of models420 and the library of layer orientation patterns 430 may be formed asdata structures stored on a storage medium of the computer system 490,such as a magnetic disk or an optical disc. The finite element analysisengine may be formed as the processor of the computer system 490 thatexecutes instructions of a computer program to analyze a design of alaminated composite device.

Each model in the library of models 420 includes internal and externaldimension information, such as length, outer circumference, outerdiameter, inner diameter, width, and/or shape, or other characteristicof a shell of a device, such as an intramedullary nail or a bone plate.Thus, devices of different configurations, shapes, and sizes may eachhave an associated model included in the library of models 420. Eachmodel is associated with at least one design in the library of designs430. The designs associated with a model have a number of layers adaptedto fit within the shell of the associated model. For example, a firstdesign associated with a first model of the nail 100 having an outerdiameter of 10 millimeters and an inner diameter of 4.4 millimeters overthe medial portion 100 c may have 20 layers, where each layer isapproximately 0.14 millimeters thick. Accordingly, the model includes ahollow central cavity 200 a having a diameter of approximately 4.4millimeters. As discussed above, the nail 100 may have a thermoplasticmaterial, or other material, disposed within the cavity 200 a. In someimplementations, the model may have an internal diameter of zero, suchthat the nail 100 is solid, but does not require a cavity to be filled.

A second model may include different external and internal diametersover the medial section than the external and internal dimensions of thefirst model. The same first design may be associated with the secondmodel where the difference between the internal and external dimensionis equal to the difference between the internal and external diametersof the first model, i.e., where the thickness of the medial portion ofthe second model is the same as the thickness of the medial portion ofthe first model. Accordingly, each of the designs may be associated withmultiple models. Furthermore, where the internal dimension of theorthopaedic fixation device is not critical, the first design may alsobe associated with nail models where the difference between the internaland external diameters of the nail model is greater than the differencebetween the internal and external dimensions of the first model.Likewise, the first design may be associated with models of bone plates,or other orthopaedic fixation devices that have a thickness equal to orgreater than the thickness of sum of the layers of the design.

As illustrated in FIG. 8, the system 400 can be used to provide a designof a laminated composite orthopaedic fixation device to a user accordingto a process 500. For example, information pertaining to a patient withwhom the device will be used can be determined (501). The informationcan include, for example, height, weight, age, and health condition ofthe patient, including a bone mineral density or other measure of bonequality of the patient, a category of device needed, an image, such as aradiograph, of the patient's bone, or other health conditions. Theinformation can be determined by a treating physician, or otherhealthcare provider, and can be input (503) to the system 400 for use inproviding a design of a laminated composite fixation device. Theinformation can be input by the physician or other healthcare providerat the treatment facility using a terminal operable with the system 400.For example, the input device 470 may be a remote terminal operable withthe computer 490 over a network, such as the Internet. Alternatively,the information may be sent to an operator of the system 490 at amanufacturer or supplier of the laminated composite fixation device.

Additionally, device information may be determined (501) by thephysician or other healthcare provider and input (503) to the system400. For example, the physician may determine a configuration of thedevice that is appropriate for use in a prescribed treatment for thepatient, such as an antegrade femoral nail. Additionally, a length orother external dimension of the device may be determined by thephysician based on the patient information, such as a radiograph of thepatient's bone to which the device is to be attached. The deviceinformation can include fixed external dimension, such as a diameter,for each section of the device, such as a diameter of the first section101, a diameter of the medial portion 100 c, and a diameter of thesecond section 103. The device information can additionally include aminimum internal diameter to ensure that a cavity of a minimum diameteris included in the device. As discussed above, this minimum diameter canbe zero, if desired. Where a minimum internal diameter is included, adesign having fewer than the maximum number of layers may be selected,as discussed in greater detail below, thereby providing a largerinternal diameter than the minimum internal diameter. Alternatively, thedevice information can include a fixed internal diameter such that athickness of the device and a size of any hollow cavity can be set.

Performance characteristics of the laminated composite device are alsodetermined (505). The performance characteristics may be determined bythe physician or other healthcare provider, based on the patientinformation and performance characteristics can then be input to thesystem 400. For example, a compression stiffness, a bending stiffness,and/or a twisting stiffness of the laminate composite device may bedetermined by the physician based on the patient's weight and the age ofthe patient. Alternatively, a maximum compression deflection, a maximumbending deflection, and/or a maximum torsion deflection can bedetermined by the physician, and the system 400 can automaticallydetermine the stiffness based on the patient information, the deviceinformation, and/or default information. The age may be used to adjustthe performance characteristics of the composite device, such as byincreasing the compression stiffness, the bending stiffness, and/or thetwisting stiffness for a younger patient, who may be more active than anolder patient. Additionally, a compression stiffness of the laminatedcomposite device may be reduced based on an age of the patient toaccount for a reduced stiffness of the patient's bone, such thatshielding of the bone by the laminated composite device may be reducedor eliminated. Similar adjustments can be made based on the bone mineraldensity, or other patient information, including imaging information.

In another example, the performance characteristics of the laminatedcomposite device may be determined based on an indication of anisotropic device, such as a metal device that may otherwise have beenprescribed for the patient. The system 400 may determine that thedimensions of the laminated composite device are substantially the samedimensions as those of the isotropic device. The system 400 may furtherdetermine the compression stiffness, the bending stiffness, and/or thetwisting stiffness of the laminate composite device based on thecompression stiffness, the bending stiffness, and/or the stiffnessstrength of the isotropic device. The determination of the performancecharacteristics based on the isotropic device may include adjustment ofthe performance characteristics of the isotropic device based on suchfactors as the age of the patient, a bone mineral density of thepatient, or other factor that may be considered by a physician inselecting the performance characteristics, as described above.

For example, an isotropic titanium device can be identified for use inselection of the performance characteristics of the laminated compositedevice. In such an example, a length, inner diameters, outer diameters,bends, and/or other dimension and shape information for the laminatedcomposite device can be determined by reference to the analogousinformation for the selected isotropic titanium device. The compressionstiffness, the bending stiffness, and/or the twisting stiffness of thelaminate composite device can be determined by automatically adjustingthe corresponding stiffness values of the isotropic titanium device.Particularly, one or more the stiffness values of the isotropic titaniumdevice may be reduced to derive the corresponding stiffness values ofthe laminated composite device.

Reducing the stiffness values can lower the occurrence of undesirablebone mineral density loss in the bone to which the device is attached,which has been observed in some applications employing metallic fixationdevices. Particularly, such bone mineral density reductions are believedto occur due to a “shielding” of the bone from loads due to a relativelyhigher stiffness of the implant compared to healthy bone. The implant,which can remain implanted in the patient for extended periods, isbelieved to bear a disproportionately large portion of forces undernormal circumstances, and, as a result, it is believed that the bodyresorbs bone minerals. While this action is believed to be accurate, itis not intended to necessarily form part of the claimed subject matter,except where specifically recited in the claims.

The system 400 then selects a model from the library of models 420according to the input device information and/or patient information(507). The model includes internal and external dimensions of thelaminate composite device that limit the size and shape of the laminatecomposite device. Accordingly, the model can be selected such that theexternal dimensions of the laminate composite device do not exceed thedimensions selected based on the patient information. The model can alsobe selected to have the minimum (or fixed) internal dimension, such thata model having the most designs associated therewith is selected,whereby chance of selecting of a design meeting the input performancecharacteristics, as discussed below, is increased.

The system 400 then selects a first design (509) from the library ofdesigns 430 that is associated with the selected model. For example, thesystem may select a first design from among the designs associated withthe selected model having a fewest number of layers, a lowestmanufacturing cost, or based on other criteria, or no criteria (i.e.,random or pseudo-random selection). The system 400 then performs afinite element analysis on the selected design (511) and determineswhether the results of the finite element analysis indicate that theselected design will exhibit the selected performance characteristics(513). If the system 400 determines that the selected design willexhibit the selected performance characteristics, then the selecteddesign is output (515). The selected design can be output in tangible orelectronic form, such as in the form of instructions operable to causean automated manufacturing system to manufacture the laminate compositedevice according to the design.

The selected design may additionally include information about a shapeof the device, which may be determined and input by a physician or otherhealthcare provider, or which may be determined by the system 400 basedon the input patient information, such as an image of the patient'sbone. If output in the form of instructions, the design can includeinstructions operable to automatically create a device having the shapeof the design. Alternatively, the device can be shaped aftermanufacture, either manually or automatically, such as by thermoforming.For example, the desired shape may be obtained by heating or otherwiseexciting the device until the plastic material is malleable, bending thedevice to the desired shape, and allowing the plastic material to set.Additionally, or alternatively, the shape of the device may be adjustedintraoperatively, such as during implantation of the device.Accordingly, some or all of the designs in the library of designs 430can be for straight devices, or devices having a default shape, based onthe configuration of the device.

If the system 400 determines that the selected design will not exhibitthe selected performance characteristics, then the system 400 selects asecond design from among the designs associated with the selected model(509). The system 400 then analyzes the second design (511) anddetermines whether second design will exhibit the selected performancecharacteristics. The selection (509), analysis (511) and determination(513) are repeated until it is determined that a selected design willexhibit the selected performance characteristics. Additionally, theprocess 500 can include a determination that no more designs areavailable for selection. Thus, where a fixed internal dimension isprovided, or a fixed thickness is provided, and relatively few designswill fit between the fixed external dimension and the fixed internaldimension, or will provide the fixed thickness, the system may not loopcontinuously in selecting designs when none of the relatively fewdesigns will exhibit the selected performance characteristics. Thesystem 400 can instead select the design having performancecharacteristics that most closely match the selected performancecharacteristics, or the system 400 can output an indication that nodesigns match the selected performance characteristics.

Referring now to FIG. 9, a flow chart illustrates a process 600 formaking the system 400. According to the process 600, the library ofmodels 420 may be created (601) by determining and storing internal andexternal dimensions and a configuration for each of multiple isotropicdevices, such as metal orthopaedic fixation devices. Performancecharacteristics of the isotropic devices may also be determined andstored in association with a corresponding model. Alternatively, oradditionally, some or all of the models may not correspond to isotropicdevices. Different models may also be included for fixed dimensioninputs and for minimum (or maximum) dimension inputs. Thus, one modelfor use with minimum internal diameter intramedullary nail inputs mayhave a first group of designs associated therewith, while another modelhaving the same external dimension but for use with a fixed internaldiameter may have a second group of designs associated therewith. Wherethe models are for fixed and minimum internal dimensions of anintramedullary nail, and each has a fixed external dimension, the secondgroup is a subset of the first group, with the first group includingadditional designs that will produce a larger internal cavity (evenwhere the cavity is subsequently filled).

The library of designs 430 may be created (603) by storing symmetricpatterns of layer orientations that include two or more opposing pairsof layer orientations. Each design of the library of designs 430 may beassociated with one or more model of the library of models 420 based onwhether the number of layers of a design will fit within the shell of amodel. Additionally, designs of greater thickness and/or more layers canbe stored as a symmetric repetition of other symmetric patterns. Thedesigns can also be stored as a symmetric repetition of anothersymmetric pattern with the inclusion of an extra layer in the center. Anumber of exemplary designs are included in table 1, in which “th”represents an angle from 0 degrees to 90 degrees, a numeral following abracketed pattern of layer angles denotes that the pattern is repeated anumber of times equal to the numeral, and the letter “S” denotes thatthe bracketed pattern, repeated a number of times equal to the numeralif one is present, is repeated in reverse. Additionally, the “†” symboldenotes that a 90 degree layer has been added between the pattern andits reverse repetition, and the symbol “‡” denotes that a 5 degree layerhas been added between the pattern and its reverse repetition.

TABLE 1 Design Number of Design layers [5/th/-th/90/-th/th/5] 7[90/th/-th/5/-th/th/90] 7 [5/th/-th/90/90/-th/th/5] 8[90/th/-th/5/5/-th/th/90] 8 [5/5/th/-th/90/-th/th/5/5] 9[5/5/th/-th/90/90/-th/th/5/5] 10 [90/90/th/-th/5/5/-th/th/90/90] 10[5/5/th/-th/90/90/90/-th/th/5/5] 11 [90/90/th/-th/5/5/5/-th/th/90/90] 11[5/th/th/-th/-th/90/-th/-th/th/th/5] 11[5/5/5/th/-th/90/90/-th/th/5/5/5] 12[5/th/th/-th/-th/90/90/-th/-th/th/th/5] 12[90/th/th/-th/-th/5/5/-th/-th/th/th/90] 12[5/5/5/th/-th/90/90/90/-th/th/5/5/5] 13[5/th/th/-th/-th/90/90/90/-th/-th/th/th/5] 13[90/th/th/-th/-th/5/5/5/-th/-th/th/th/90] 13 [5/th/-th/90/-th/th/5]S 14[5/th/-th/90/-th/th/5/5/5/th/-th/90/-th/th/5] 15[5/th/-th/90/-th/th/5/90/5/th/-th/90/-th/th/5] 15 [5/th/-th/90]2S 16[5/5/5/th/th/-th/-th/90/90/-th/-th/th/th/5/5/5] 16[5/5/th/th/-th/-th/90/90/90/90/-th/-th/th/th/5/5] 16[90/90/th/th/-th/-th/5/5/5/5/-th/-th/th/th/90/90] 16[5/5/5/th/th/-th/-th/90/90/90/-th/ 17 -th/th/th/5/5/5][5/5/th/th/-th/-th/90/90/90/90/90/-th/ 17 -th/th/th/5/5][5/5/th/th/-th/-th/90/90/5/90/90/-th/ 17 -th/th/th/5/5][90/90/th/th/-th/-th/5/5/5/5/5/-th/ 17 -th/th/th/90/90][90/90/th/th/th/th/5/5/90/5/5/th/th/th/th/90/90] 17[5/5/th/-th/90/-th/th/5/5]S 18 [5/5/5/th/th/-th/-th/90/90/90/90/-th/ 18-th/th/th/5/5/5] [5/5/th/th/-th/-th/90/90/5/5/90/90/-th/ 18-th/th/th/5/5] [5/5/th/-th/90/-th/th/5/5/90/5/5/th/-th/90/ 19-th/th/5/5] [5/th/th/-th/-th/90/90/-th/th/5/5/th/-th/90/90/ 20-th/-th/th/th/5] [5/5/th/-th/90/90/-th/th/5/5/90/5/5/th/ 21-th/90/90/-th/th/5/5] [5/5/th/-th/90/90/90/-th/th/5/5]S 22[5/5/th/-th/90/90/90/-th/th/5/5]S† 23 [90/90/th/th/5/5/5/th/th/90/90]S‡23 [5/th/th/-th/-th/90/90/-th/-th/th/th/5]S 24[90/th/th/-th/-th/5/5/-th/-th/th/th/90]S 24 [5/th/-th/90/90/-th/th/5]324 [90/th/-th/5/5/-th/th/90]3 24 [5/5/5/th/-th/90/90/-th/th/5/5/5]S† 25[5/th/th/-th/-th/90/90/-th/-th/th/th/5]S† 25[90/th/th/-th/-th/5/5/-th/-th/th/th/90]S‡ 25[5/th/th/-th/-th/90/90/90/-th/-th/th/th/5]S 26[90/th/th/-th/-th/5/5/5/-th/-th/th/th/90]S 26[5/th/th/-th/-th/90/90/90/-th/-th/th/th/5]S† 27[90/th/th/-th/-th/5/5/5/-th/-th/th/th/90]S‡ 27 [5/th/-th/90/-th/th/5]2S28 [5/th/-th/90/-th/th/5]2S† 29[5/th/-th/90/-th/th/5/5/5/th/-th/90/-th/th/5]S 30[5/th/-th/90/-th/th/5/90/5/th/-th/90/-th/th/5]S 30

Alternatively or additionally, non-symmetric patterns and/or patternswith less than two (including zero) opposing pairs or layer orientationscan be stored.

The finite element analysis engine 440 may be created (605) by selectingone or more parameters for operation of a finite element analysisprogram. A laminate composite device of a first design is thentheoretically tested using the finite element analysis program and theselected parameter(s) for operation (607) to generate theoretical testresults. Additionally, the laminate composite device of the first designis physically tested (609) to generate physical test results. Thetheoretical and physical test results are compared (611) to determinewhether the theoretical test results are similar to the physical testresults. If the theoretical and physical test results are similar, thenthe finite analysis engine is validated (613). If the theoretical andphysical test results differ substantially, then the parameters foroperation are adjusted (615), and the theoretical testing of thelaminate composite device of the first design is repeated (607) togenerate new theoretical test results, which are then compared (611) tothe physical test results.

The library of models 420, the library of designs 430, and the validatedfinite element analysis engine 440 may be combined (617) with a computersystem having a processor 410, a storage device 450, and an input/outputmodule 460. A computer program is stored (619) on the storage device 450such that the computer program is operable with the processor 410. Thecomputer program can include instructions that, when executed by theprocessor 410, are operable to cause performance of the process 500 forproviding a design for a laminated composite device.

Described below are implants made from a carbon fiber-reinforcedcomposite material or a fiber-reinforced biocompatible polymer, such aspolyetheretherketone (PEEK) or polyaryletherketone (PAEK). The implantmay be a nail, plate, hip stem, shoulder stem, spine cage or otherimplantable device for orthopaedic application. The features describedin conjunction with some of the embodiments have been illustrated as anantegrade femoral nail or a bone plate, but these features may beequally applied in at least a humeral, tibial, radial, ulnar,clavicular, and fibular application. Further, while the featuresdescribed in conjunction with some of the embodiments have beenillustrated as trauma applications, they could equally be applied toreconstructive products.

FIGS. 10 and 11 illustrate an intramedullary nail 100 mounted within abone 1000. The intramedullary nail may have one or more features asdescribed above. In the depicted embodiments, the intramedullary nail100 is made from a carbon fiber-reinforced composite material or afiber-reinforced biocompatible polymer. As an example, the material maybe the ENDOLIGN product available from Invibio Inc., located at 300Conshohocken State Road, West Conshohocken, Pa. ENDOLIGN is a registeredtrademark of Invibio Limited. As another example, the material may be ahigh strength version of polyetheretherketone, commonly known as PEEK.In some embodiments, the intramedullary nail 100 includes a hole 713,which may be used to receive a lag screw (not shown). In someembodiments, the intramedullary nail 100 may be cannulated.

In FIGS. 10 and 11, the intramedullary nail 100 includes radio-opaquemarkers 712. The radio-opaque markers 712 may be imbedded metal wireplaced at various locations on or in the intramedullary nail 100. Oneset of markers may be placed along the axis of the intramedullary nail100 on the medial and lateral side. These markers are used with animaging device in a medial/lateral view to determine the proper rotationof the intramedullary nail 100 to ensure that the lag screw is placedinto the center of the bone 1000. It is accomplished by aligning the twomarkers 712 with a center of the bone 1000 as is shown in FIG. 11.

The radio-opaque markers 712 may be made from a variety of materials,including but not limited metals (such as 316 SST, Cobalt Chrome, Ti 6Al4 V, tantalum), ceramics (such as TCP, HA, Barium Sulfate), resorbablematerials such as magnesium, or polymers. The radio-opaque markers 712can take the shape of a single element or multiple elements. Theradio-opaque markers 712 may be continuous or non-continuous. Theradio-opaque markers 712 may mark the axis of a screw path withindividual markers on each side of the intramedullary nail 100, or havemultiple markers on each side that note the edges of the screw path.

In some embodiments, a fastener may be used in conjunction with thenail. As examples, the fastener may be a locking screw, a lag screw, ora compression screw. The fastener may be made from metal, polymer, or acomposite material. The fastener may include a radio opaque marker tohelp with alignment or depth insertion. The fastener may be threaded andmay include a radio opaque marker only on the thread portion to providean indication of bone purchase.

FIGS. 12 and 13 illustrate another use of the radio-opaque markers. Inthe depicted embodiment, one set of radio-opaque markers 714 is placedon the anterior and posterior side of the intramedullary nail 100 in thesame plane as the axis of the lag screw hole 713. These markers are usedin conjunction with an imaging device in an anterior/posterior view todetermine the correct depth of the nail by aligning the markers with thebone 1000.

FIGS. 14-17 illustrate an alternative placement of radio-opaque markers.In the depicted embodiments, the radio-opaque markers 715 are placed oneach side of the screw path. In FIG. 15 the imaging device is misalignedwith the markers and aligned in FIG. 16. FIG. 17 illustrates aperspective view of the placement of four markers 715. In the embodimentdepicted in FIG. 17, four markers are shown but those of ordinary skillin the art would understand that two or more markers may be used.Further, it should be noted in the embodiment depicted in FIG. 17 thatthe markers are not placed in the thinnest area next to the hole. Thismay be significant for the structural integrity of the implant.

FIG. 18 illustrates another embodiment of the intramedullary nail 100.In the depicted embodiment, the intramedullary nail 100 includes a core716 surrounded by a polymer or composite material. The core 716 may bemade from any biocompatible material, such as a metal, ceramic, polymer,or a composite. In the depicted embodiment, the core 716 has acylindrical cross-section but other geometries may be equally used. Thecore 716 may be placed over the mandrel during manufacture of the nailor used in place of a mandrel.

FIG. 19 illustrates another embodiment of the intramedullary nail 100.The intramedullary nail 100 may include one or more openings at a distalend. In the depicted embodiment, the intramedullary nail 100 includes ahole 718 and a slot 720, and each opening includes an insert 721. Theinsert 721 may be integral or embedded into the intramedullary nail 100.The insert 721 may be made from any biocompatible material, such as ametal ceramic, polymer, or a composite. The insert 721 may beradio-opaque such that a more distinct image in the radiograph makingthe technique of acquiring “perfect circles” easier. In someembodiments, the insert 721 may include a flange. For example, theflange may conform to the exterior surface of the nail. The insert 721may provide additional strength and abrasion resistance. For example,the insert 721 may prevent an instrument, such as a drill, from wearingof the composite material. Those having ordinary skill in the art wouldunderstand that the location of the hole 718 and the slot 720 may bereversed. Further, additional holes or slots may be provided, and insome embodiments one of the hole or slot may be omitted.

FIGS. 20 and 21 illustrate another embodiment of the intramedullary nail100. The intramedullary nail may have one or more features as describedabove. In the depicted embodiment, the intramedullary nail 100 includesembedded or in-molded electronic components. As examples, the electroniccomponents may include one or more of a transceiver 722, wire 724, andstrain gauge/circuit board 726. As yet another example, theintramedullary nail 100 may include a thin-film battery (not shown),such as the device disclosed in U.S. Pat. No. 6,632,563 to Krasnov etal. or U.S. Pat. No. 4,960,655 to Hope et al. The '563 patent and the'655 patent are herein incorporate by reference. The thin-film batterymay form part of an energy scavenging and storage device. Scatteredambient energy present in the form of ubiquitous vibrations, such asheat or radiation, can be harvested from a variety sources by utilizingpiezoelectric, thermoelectric, or photovoltaic generators. The harvestedenergy can then be stored in the thin-film battery. Embedding electroniccomponents within the orthopaedic fixation device provides theadvantages of increased biocompatibility and reduced interference fromelectromagnetic forces.

As an example, the energy scavenging device may be one or morethin-film, all-solid-state, lithium energy cells provided by Front EdgeTechnologies of Baldwin Park, Calif. The energy cell may be placedbetween two layers of carbon fiber. As an example, the layers may be at90 degrees to each other. The energy cell may be located squarely in thegeometric center of the two layers. A polyester-coated flat flexiblecable (FFC) may be used to connect the energy cell to other components.As an example, the flat flexible cable may be obtained from NicomaticInc. of Warminster, Pa. The energy cells may be pre-sealed along theedges and over the electrodes with a two component low-viscosity epoxyand cured at room temperature. As an example, the epoxy may be Epotech,#301. The curing time may be from 18-30 hours, and more particularly 24hours.

In some embodiments, the intramedullary nail 100 may be patientspecific. The intramedullary nail may have one or more features asdescribed above. As best seen in FIG. 22, portion 728 may be removed toachieve a custom length, hole 730 may be added, hole 732 may be changedfrom a static hole to a dynamic hole, and a radius R may be changed toachieve to match a patient's bone. These patient-specific modificationsmay be performed pre-operatively or intraoperatively. A polymer materialpresents the advantage of 5 intraoperatively adjusting the orthopaedicfixation device. In the past, bending a metal nail required a machinestrong enough to bow the nail. Such a machine is generally considered tobe too cost prohibitive for placement in an operating room. For apolymer device, other forms of energy may be used to reshape theintramedullary nail. As examples, such energy may be in the form of heator acoustic energy, such as ultrasound. As an example, energy may be oapplied to the intramedullary nail and then manually shaped.Alternatively, the intramedullary nail may be placed in a three-rollbender with the energy directed between the rollers for intraoperativelyshaping the intramedullary nail. Similarly, additional holes or otherfeatures may be obtained by applying energy in conjunction with aspecific geometric fixture to control shape and location. 5

FIG. 23 illustrates another embodiment of the intramedullary nail 100.The intramedullary nail may have one or more features as describedabove. In the depicted embodiment, a protective sleeve or capsule 734may be embedded within the intramedullary nail 100. The protectivesleeve 734 may be made of a ceramic material or a metal with a heatresistant coating. The material may be selected to reduce the chance ofelectromagnetic0 interference. The protective sleeve 734 may be used toprotect an electronic component, such as a sensor. The protective sleeve734 may be used to provide a hermetic seal. The protective sleeve 734may be placed at any radial depth of the intramedullary nail 100.

FIG. 24 illustrates still another embodiment of the intramedullary nail100. The intramedullary nail may have one or more features as describedabove. In the5 depicted embodiment, the intramedullary nail 100 includesan in-molded cannulation 736 and one or more in-molded holes 738. Inother words, the cannulation or the hole is manufacturedcontemporaneously with the intramedullary nail and is not a result of alater manufacturing step. A mandrel or similar device may be used tocreate such voids. FIG. 24 also illustrates the embedded sleeve orcapsule 734.

FIGS. 25 and 26 illustrate yet another embodiment of the intramedullarynail 810. In the depicted embodiment, the intramedullary nail 810 has agenerally “U” or “C” shaped cross-section. The depicted embodiment iseasier to manufacture than a cannulated intramedullary nail but stillallows for the use of a guide rod. The intramedullary nail 810 may bemanufactured by assembling layers of a composite and then shaping or byshaping in manufacture, such as by molding.

FIGS. 27-30 illustrate an intramedullary nail 820 with a groove orchannel 830. The depicted embodiments are easier to manufacture than acannulated intramedullary nail but still allows for the use of a guiderod. The intramedullary nail 820 may also include a proximal hole 840, adistal hole 850, and a tapered tip 860. In the embodiment depicted inFIG. 29, the proximal hole 840 is generally cylindrical and the distalhole 850 is slotted but other shapes may equally be used. In theembodiment depicted in FIG. 30, the intramedullary nail 820 has atrapezoidal shape but other shapes may also be used.

In operation, a guide rod is placed into an intramedullary canal. Thefracture is reduced. The intramedullary nail 820 is placed in theintramedullary canal with the guide rod riding in the channel 830. Theguide rod is removed, and the intramedullary nail 820 is locked intoplace.

FIGS. 31 and 32 illustrate bone plates 700, 702. The bone plates mayhave one or more features as described above. The bone plates 900, 902are made from a carbon fiber-reinforced composite material or afiber-reinforced biocompatible polymer. As an example, the material maybe the ENDOLIGN product available from Invibio Inc., located at 300Conshohocken State Road, West Conshohocken, Pa. As another example, thematerial may be a high strength version of polyetheretherketone,commonly known as PEEK. The bone plates 900, 902 include openings 903,which may be machined or in-molded. The openings 903 may be threaded ornon-threaded. Threaded openings may be partially or fully threaded andmay have single or multiple leads. The openings 903 may be a hole, slot,or provisional mounting holes. The openings 903 may be reinforced. Theopenings 903 may include locking tabs which may engage with a lockingscrew.

FIGS. 33 and 34 illustrate a bone plate 910 with one or more in-moldedfeatures 912, such as an arcuate cutout. In other words, the feature ismanufactured contemporaneously with the bone plate and is not a resultof a later manufacturing step.

FIG. 35 illustrates another embodiment of the bone plate 910 with one ormore stiffeners or structural reinforcements 914 surrounded by a polymeror composite material. The structural reinforcements 914 may be madefrom any biocompatible material, such as a metal, ceramic, polymer, or acomposite.

FIG. 36 illustrates another embodiment of the bone plate 910 with one ormore insertion elements 916. The insertion element 916 is placedrelative to an opening to reinforce the opening. In some embodiments,the insertion element may be threaded. The insertion elements 916 may bemade from any biocompatible material, such as a metal ceramic, polymer,or a composite.

FIG. 37 illustrates another embodiment of the bone plate 910. The boneplate 210 may include one or more connectors 918. The connector 918 maybe used to connect one or more bone plates 910. This may allow for apatient-specific bone plate. For example, bone plates may be attached inseries to obtain a particular length. U.S. Pat. No. 7,090,676 to Huebneret al. disclose a method of connecting adjacent bone plate portions. The'676 patent is herein incorporated by reference. U.S. Patent ApplicationPublication No. 2008/0097445 A1 to Weinstein discloses another method ofconnecting adjacent bone plate portions. The '445 application is hereinincorporated by reference.

FIG. 38 illustrates a patient specific bone plate 920. The shape of thebone plate 920 is adjusted intraoperatively through the application ofenergy to match a patient's anatomy, to provide a buttress, to compressa fracture, or to distract a fracture. A polymer material presents theadvantage of intraoperatively adjusting the bone plate. In the past,bending a bone plate required a machine strong enough to bend metal.Such a machine is generally considered to be too cost prohibitive forplacement in an operating room. For a polymer device, other forms ofenergy may be used to reshape the bone plate. As examples, such energymay be in the form of heat or acoustic energy, such as ultrasound. As anexample, energy may be applied to the bone plate and then manuallyshaped. In one particular method, a patient's bone is analyzed to definea contour, and the bone plate is then modified relative to the contour.In some embodiments, the bone plate is modified to match the contour. Inother embodiments, the bone plate is modified such that the bone platehas potential energy and imparts energy to the bone when implanted tocompress or distract the bone. For example, the bone plate may be bentto provide a spring-bias when applied to the bone.

FIG. 39 illustrates an intramedullary nail 950. The intramedullary nailmay have one or more features as described above. In the depictedembodiment, the nail 950 is made from a polymer or a composite and isimplanted in a bone 1000. The nail 950 includes one or more sleeves. Inthe depicted embodiment, the nail 950 includes a first sleeve 960 and asecond sleeve 970, but any number of sleeves may be used. The sleeves960, 970 are made from an abrasion resistant, biocompatible material,such as stainless steel, titanium, or ceramic. The sleeves 960, 970 maybe in the form of a band or cylinder pressed onto the nail 950. Thesleeves 960. 970 may incorporate through holes. For example, sleeve 970may have through holes for locking the nail in place with a fastener.

FIG. 40 illustrates an intramedullary nail 980. The nail 980 includes aproximal portion 982, a working portion 984, and a distal portion 986.The working portion 984 is made from a polymer or composite and mayincorporate one or more features described above in conjunction withintramedullary nails. The proximal and distal portions 982, 986 are madefrom a biocompatible, abrasion resistant material. As an example, theproximal and distal portions 982, 986 may be made from stainless steel,titanium, or ceramic. The proximal portion 982 may include features,such as a slot and threaded hole, for connecting an instrument, such asan insertion handle, to the nail 980. The distal portion 986 may includea vertical slot to bifurcate a portion thereof. The proximal portion982, the working portion 984, and the distal portion 986 may becannulated.

The working portion 984 may be used to customize the stiffness of theconstruct. Further, the working portion 984 may be used to customizedimensions, such as length, inner diameter, and outer diameter. As anexample, the outer diameter may be sized and dimensioned to match thebone, and the inner diameter may be selected to achieve a desiredstiffness. The working portion 984 may have any number ofcross-sections, including, but not limited to, cylindrical, octagonal,hexagonal, triangular, rectangular, trapezoidal, u-shaped, c-shaped, andd-shaped. Further, the working portion 984 may match a cross-section ofthe proximal portion 982 and transition to a cross-section of a distalportion 986, or vice versa.

The working portion 984 may be attached to the proximal or distalportion in any number of different ways. As examples, the workingportion may be connected to one of the distal and proximal portions 982,986 by ultrasonic welding, by knurling the distal and proximal portions982, 986 and press fitting the working portion 984 thereon, by knurlingthe distal and proximal portions 982, 986 and molding the workingportion 984 thereon, by a threaded connection, by a snap-fit connection,or by a pin connection. In one particular embodiment, the distal andproximal portions 982, 986 have a female receptacle and the workingportion 984 has a male connector, or vice versa. In another embodiment,one or more pins are used to connect the working portion 984 to one ofthe distal and proximal portions 982, 986. The pins may be placed atdifferent layers and/or orientations.

Additionally, text may be printed on an implant with an iron-basedradio-opaque ink so that it appears on radiographs. The process used forapplying the ink is the same as is used currently to apply ink to aninstrument, which is through Pad Printing. The text may include thecompany logo, implant size, implant lot number, quality control number,Left or Right (if appropriate), and pertinent notes or warnings (e.g.,“For use with Gold Guide Drop ONLY”). Further, the text may includepersonalized patient information, such as patient name, patientidentification information, social security number, nickname, favoritesports team name, sports team mascot, or sports team expression (e.g.,“GO BOILERS!” or “GEORGIA BULLDOGS.”).

Another process to show text and graphical information on the implantradio-graphically may be achieved by molding thin metal sheets in or onthe body of the implant. These sheets can contain the informationdesired and when observed under radiographs it is viewable. Theinformation can be machined, laser etched, or chemical etched into thethin metal sheet.

In another embodiment, there is provided a bone plate with radiographicmarkers located at an edge or proximate to a feature, such as a hole.The radiographic markers may be used to verify a bone plate locationwith an imaging device. This may be of an advantage in some procedures,such as minimally invasive surgery.

The implants may be made using various methods of manufacturing, such ascompression flow molding, laminate, injection molding, vacuum assistresin transfer molding, vacuum induced preform relaxation, machining ofraw or semi-finished stock, 3D weaving, mandrel wound, andthermoforming. If a mandrel is used, it may be made from a singlesection or a multiple section.

In some embodiments, the fiber layup and/or fiber orientation may becontrolled to adjust the overall strength of the implant. In someembodiment, advanced fiber placement technology may be used to controlor vary the stiffness of the implant in particular locations. Typically,fiber layers are placed in 0, ±45 and 90 degree plies. However, bycontinuously varying fiber angles, the stiffness of particular portionsof the implant can also be varied. The fiber angles may be varied as afunction of the circumferential coordinate or longitudinal coordinate ofa cylinder or similar object.

Further, in some embodiments, the fibers may be laid in a threedimensional weave pattern or a quasi-three dimensional weave pattern tosubstantially reduce the risk of delamination. The phrase “quasi-threedimensional weave pattern” refers to weaves having in-plane yarns in theadjacent layers interlocked to one another to form overallthree-dimensional networks. Generally, three dimensional weaves havesome yarns oriented in the thickness direction, which do not directlycontribute to the in-plane strength of the composite material. Theseyarns may cause kinks to the in-plane yarns at points where they areinserted and may become weak points in the composites due to the highstress concentrations. Quasi-three dimensional weaves have yarns thatare primarily located in the plane of the weave. The yarns areinterlocked not only with the cross yarns of their own layer, but alsogo deeper into the weave to interlock with the yarn of the adjacentlayer. Although undulations of the in-plane yarns can be clearlyidentified, none of the yarns is specifically oriented in the thicknessdirection. The contribution of the in-plane yarns to the in-planeproperties, hence, can be largely preserved.

In one embodiment, a medicament containment device containing amedicament, such as for example an antibiotic, is attached to animplant. The medicament containment device can degrade upon exposure toenergy, such as energy from an energy source. The implant, including themedicament containment device, is implanted or inserted into anenvironment such as a patient's body. An energy source can be usedoutside the patient's body, but in proximity to the implant, to applyenergy to the medicament containment device. Upon exposure to theenergy, the medicament containment device can disintegrate, degrade, orotherwise alter in structure or composition or both, partially ortotally, sufficient to allow a medicament to penetrate (hereinafter“degrade”) and release at least part of the medicament into theenvironment. As an example, the medicament can kill and/or disruptbacterial cells or other infectious cells that form in proximity to theimplant. “Medicament” as used herein may include any medicine or othercomposition that can be used to promote healing or recovering, such asfrom an infection (whether bacterial, viral, or otherwise). Examples ofsuitable medicament for use in connection with various embodimentsincludes osteoblast affecting agents, osteoclast affecting agents,antibiotics, anti-inflammatory agents, pain medication, osteogenicfactors, prostaglandins, radio-markers, angiogenic factors,vasodilators, growth factors, or a combination of any of the above.

In some embodiments, all or portions of the fibers and/or the resin maybe resorbable. As examples, the resin may be resorbable, the fibers maybe resorbable, or a percentage (such as one-half or one-third) of fibersmay be resorbable.

Typically, a fastener is used to secure the orthopaedic fixation devicewithin or to bone. The fastener may be completed threaded or have adistal threaded end portion. However, a screw thread may disrupt acarbon-fiber reinforced polymer and produce unwanted particles. Othermethods of securing the orthopaedic fixation device within or to boneinclude gluing the fixation device to bone, inserting a non-threadedfastener through the fixation device and gluing it to bone, inserting anon-threaded fastener through the fixation device and bone and expandingthe fastener, inserting a non-threaded fastener through the fixationdevice and bone and ultrasonically welding the fastener to the fixationdevice, and inserting a non-threaded fastener through the fixationdevice and bone and shrinking the fixation device around the fastener.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made without departingfrom the spirit and scope of the claimed invention. For example, whilethe fibers of each layer of the laminated composite orthopaedic fixationdevice of some implementations have been described as generally straightand parallel, in other implementations, the fibers within each layer maybe woven, braided, or twisted into groups of fibers, which can bearranged in parallel within the layer and embedded within, orimpregnated with, thermoplastic material. Furthermore, the fibers can bewoven or braided to form three dimensional structures. Similarly, thefibers can be arranged to interconnect with fibers of an adjacent layerto form a three dimensional construct. Additionally, in someimplementations, a composite tape can include fibers or groups of fiberswoven or braided into a narrow sheet, where the width of the sheet isapproximately equal to the width of the tape. The fibers can then beembedded within, or impregnated with, thermoplastic material. Similarly,the fibers of one or more layer may be discontinuous, such as choppedfibers. In some implementations, a layer of thermoplastic materialwithout fibers can be included between one or more of the fiberreinforced composite layers.

In some implementations, the composite material can also includedifferent polyketone materials, such as Polyaryletherketone (PAEK), orother biocompatible thermoplastic materials. Similarly, other groups ofbiocompatible materials that are non-hygroscopic, or otherwise maintainstructural characteristics, can be used.

In some implementations, the nail 100 can include features to provideadditional benefits such as reduction of debris released into the bodythat can result from contact between the nail 100 and other implantsand/or instruments during or after the implantation. For example, thenail 100 may be formed without any apertures 111 in each of the firstsection 101 and the second section 103. The nail 100 can includeprojections such as hook-shaped members or claws on the first section101 and/or second section 103 for engaging the nail 100 to the innercortical walls of the bone canal. The projections can be an integralpart or separate entities to the nail 100. In some implementations, thenail 100 is inserted in the bone while the projections are retracted andlater expanded for engagement with the cortical walls. In otherimplementations, the nail 100 can include apertures having metal orthermoplastic inserts, bushings, or sleeves to reduce or eliminatecontact between a fastener and carbon fibers. Additionally, the nail 100may have threaded or non-threaded apertures 111 where the pin P or otherfastener, can be secured via biocompatible adhesive, ultrasonic welding,or a shape memory screw and/or insert.

Additionally, though the nail 100 has been described as including asingle medial portion 100 c, two or more separate portions may beincluded, where each portion is formed from multiple layers of afiber-reinforced composite material, and the portions may have differentcircumference dimensions. Additionally, the listing of designs in tableone is not an exhaustive list, and other designs can be included in thelibrary of designs 430 and the nail 100 or other orthopaedic fixationdevice can have other designs. Accordingly, other embodiments are withinthe scope of the following claims.

The invention claimed is:
 1. An intramedullary (IM) nail comprising: alongitudinal axis; a head portion; a shaft portion; a transition regionbetween the head portion and the shaft portion; at least one aperturefor receiving a fastener; and a plurality of radio-opaque markersincluding first, second, third and fourth radio-opaque markers, thefirst, second, third and fourth radio-opaque markers being positionedadjacent to the at least one aperture, the first, second, third, andfourth radio-opaque markers being adapted and configured so that, inuse, the first, second, third, and fourth radio-opaque markers arecapable of illustrating when an imaging device is properly aligned withthe at least one aperture; wherein the IM nail includes a plurality oflayers, each layer of the plurality of layers including a thermoplasticcomponent and a fiber component, each layer of the plurality of layershaving a selected fiber angle pattern; wherein the plurality of layersinclude at least a first layer, a second layer, and a third layer, thesecond layer being wrapped about the first layer so that the secondlayer has a different fiber angle pattern than the first layer, and thethird layer is wrapped about the second layer so that the third layerhas a different fiber angle pattern than the second layer.
 2. The IMnail of claim 1, wherein, for each layer of the plurality of layers, thefibers are orientated generally parallel with respect to a longitudinalaxis of that layer.
 3. The IM nail of claim 1, further comprising anembedded electronic component.
 4. The IM nail of claim 1, whereinselected fiber angle patterns of the layers are selected such that theIM nail exhibits a selected stiffness characteristic.
 5. The IM nail ofclaim 1, further comprising an exterior coating of a thermoplasticmaterial with substantially no fiber component.
 6. The IM nail of claim5, wherein the exterior coating comprises a layer in the form of a tapeor tow.
 7. The IM nail-of claim 1, wherein the head portion comprises agreater number of layers than a number of layers of the shaft portion.8. The IM nail of claim 1, wherein the at least one aperture includes afirst aperture and a second aperture, the first aperture being locatedwithin the shaft portion, the second aperture being located within thehead portion, the first aperture including the first, second, third, andfourth radio-opaque markers, the second aperture including first,second, third and fourth radio-opaque markers, the first, second, thirdand fourth radio-opaque markers of the second aperture being positionedadjacent to the second aperture, the first, second, third, and fourthradio-opaque markers of the second aperture being adapted and configuredso that, in use, the first, second, third, and fourth radio-opaquemarkers of the second aperture are capable of illustrating when animaging device is properly aligned with the second aperture.
 9. The IMnail of claim 8, further comprising a sensor spaced apart from each ofthe first and second apertures.
 10. The IM nail of claim 8, furthercomprising a sleeve disposed in each of the first and second apertures,the sleeves being configured to receive the fasteners therein.
 11. TheIM nail of claim 8, wherein the fibers of each layer are routed aroundthe first and second apertures.
 12. The IM nail of claim 1, wherein eachlayer of the plurality of layers is constructed from a continuousfiber-reinforced material, the continuous fiber-reinforced materialhaving a length and a width, each fiber of the continuousfiber-reinforced material being generally aligned in parallel with thelength of the continuous fiber-reinforced material.
 13. The IM nail ofclaim 1, wherein the second layer is wrapped about the first layer suchthat the longitudinal axis of the fibers of the second layer areoriented at approximately a forty-five degree angle with respect to thelongitudinal axis of the IM nail, and the third layer is wrapped aboutthe second layer such that the longitudinal axis of the fibers of thethird layer are oriented at approximately a negative forty-five degreeangle with respect to the longitudinal axis of the IM nail.
 14. The IMnail of claim 13, wherein the first layer of the IM nail is wrappedgenerally perpendicular to the longitudinal axis of the IM nail.
 15. TheIM nail of claim 13, further comprising a fourth layer wrapped about thethird layer, the fourth layer being wrapped about the third layer sothat the fourth layer has a different fiber angle pattern than the thirdlayer.
 16. The IM nail of claim 15, wherein the fibers of the fourthlayer are oriented generally parallel to the longitudinal axis of the IMnail.
 17. The IM nail of claim 1, wherein the head portion has a firstcircumference, the shaft portion has a second circumference, the secondcircumference being smaller than the first circumference, the transitionregion having a decreasing circumference along the longitudinal axisfrom the first circumference.
 18. The IM nail of claim 1, wherein the IMnail includes a solid central core.
 19. The IM Nail of claim 1, whereinin use, the first and second radio-opaque markers are capable of beingaligned with respect to each other and the third and fourth radio-opaquemarkers are capable of being aligned with respect to each other when animaging device is properly aligned with the at least one aperture. 20.An intramedullary (IM) nail for implantation within an intramedullarycanal of a long bone, the IM nail comprising: a body portion having alongitudinal axis, the body portion including at least one aperture forreceiving a fastener and first, second, third and fourth radio-opaquemarkers embedded within the body portion of the IM nail, the first,second, third and fourth radio-opaque-markers positioned adjacent to theat least one aperture, the first, second, third, and fourth radio-opaquemarkers being adapted and configured so that, in use, the first andsecond radio-opaque markers are capable of being aligned with respect toeach other and the third and fourth radio-opaque markers are capable ofbeing aligned with respect to each other when an imaging device isproperly aligned with the at least one aperture; wherein the bodyportion includes a plurality of layers, each layer of the plurality oflayers being constructed of a composite material including athermoplastic component and a fiber component; wherein the plurality oflayers include at least a first layer, a second layer, and a thirdlayer, the second layer being wrapped about the first layer such that alongitudinal axis of the fibers of the second layer are oriented at aselect angle with respect to the longitudinal axis of the body portionof the IM nail, and the third layer is wrapped about the second layersuch that a longitudinal axis of the fibers of the third layer areoriented at a select angle with respect to the longitudinal axis of thebody portion of the IM nail; wherein the select angle is one ofapproximately a five to a forty-five degree angle, or approximately anegative five to forty-five degree angle.